Slant-gap plasmonic nanoantennas for optical chirality engineering and circular dichroism enhancement.

We present a new design of plasmonic nanoantenna with slant gap for optical chirality engineering. At resonance, the slant gap provides highly enhanced electric field parallel to external magnetic field with a phase delay of π/2, resulting in enhanced optical chirality. We show by numerical simulations that upon linearly polarized excitation our nanoantenna can generate near field with enhanced optical chirality which can be tuned by the slant angle and resonance condition. Our design allows chiral analysis with linearly polarized light and may find applications in circular dichroism analysis of chiral matter at surface.